Current prosthetic limbs for the upper and lower extremity typically include a residual limb socket, an alignment system, and a functional component such as a knee, foot, or hand. For any prosthetic limb, a prosthetic socket is the portion of the prosthesis that is designed to fit and interface the residual limb with the rest of the prosthetic components. The socket is the structural component of the prosthesis that contains the residual limb, and provides connection to the other components. The prosthetic socket is an important part of the prosthetic limb; if it does not operate properly, utility of the distal components can be severely compromised.
Positive and negative molds of the residual limb typically play a central role in the making a residual limb prosthetic socket. For example, after a professional prosthetist has fully evaluated a patient's condition and needs, the prosthetist casts a negative mold of the residual limb using plaster or fiberglass casting tape. This negative mold is filled with Plaster of Paris and allowed to harden. The negative cast is then peeled off to reveal the newly formed positive mold. This positive mold may then modified by the prosthetist in an attempt to create a positive form that supports the creation of a limb socket that distributes pressure optimally on the residual when the socket is worn. The actual prosthetic socket is then fabricated over this positive mold. The positive mold is broken and removed from the fabricated socket, and the prosthetic socket may then be cut or further modified to fit its intended location and buffed.
In addition to the aspects of fabrication process just described, additional steps of the fabrication process may include making and integrating flexible inner liners, locking mechanisms, alignment mechanisms, and other components to create the final prosthetic socket product.
When complete, the socket is typically tested on the patient for fit and for the patient's subjective sense of how it feels. In spite of modifications that are possible, and in spite of level of optimization made possible by liners and locking and alignment mechanisms, the form, as provided by the positive mold and as reflected in the resultant socket dominate variables associated with the fit of the socket and patient satisfaction. By this conventional fabrication approach, the degree of possible modification of the limb socket to optimize the fit of the residual limb socket is actually quite limited. Accordingly, it is common practice to make a number of “check sockets” or “diagnostic sockets” from which the best option is chosen as the final product for the patient.
As may be understood from the foregoing brief summary of a conventional prosthetic fabrication process, there are aspects of the process that are less than satisfactory, largely associated with the centrality of physical molds within the process that transfer size and shape information from the residual limb that is reflected in the final prosthetic socket product. The process is drawn out and time consuming, and inexact. And the product, when formed and however satisfactory, is substantially fixed in form, and not readily modifiable. The residual limb, itself, is not fixed in form, and may vary in shape and condition with time as the patient ages, and as the residual limb changes in response to use and environmental conditions. Developments in the field that could improve these shortcomings would be welcome in the medical market, particularly in areas of the developing world where patients with amputated limbs are medically underserved and resources are limited.